Perhalomethylcyclohexadienes



Patented May 23, 1950 UNITED STATES PATENT OFFICE PERHALOMETHYLCYCLOHEXADIENES Waldo B. Ligett, Detroit, Mich., and Earl T. Mc-

Bee, La Fayette, and Vincent V. Lindgren, West Lafayette, Ind., assignors to Purdue Research Foundation, West Lafayette, Ind., a corporation of Indiana No Drawing. Application November 13, 1945, Serial No. 628,374

3 Claims. (01. 260 -648) tain new, non-flammable halocarbons, which because of their said characteristics are useful as dielectrics and heat-transfer media. In addition, the compounds are useful as chemical intermediates.

The compounds may be prepared, for example, by treating the appropriate halogenated cyclic compound, preferably an aromatic halocarbon, with silver difluoride in a liquid-phase reaction, wherein the silver difluoride is suspended in a fluorocarbon and the aromatic halocarbon is added thereto. Another way in which the compounds may be prepared comprises treatment of an appropriate halogenated cyclic compound, e. g., pentachlorobenzotrifluoride, in a threestep reaction, using, for example, in the first step in the process, bromine trifluoride. The product from the bromine trifluoride reaction is then treated with antimony pentailuoride to replace, w ith fluorine, any bromine which may have been introduced in the previous step. As a flnal step, the product from the antimony pentafluoride treatment is dehalogenated with a suitable agent, e. g., zinc dust, and rectified, yielding a perhalomethylcyclohexadiene.

The invention herein is not concerned with the process of manufacture or the apparatus employed, but is concerned solely with the new group of compounds herein described and claimed. The following example illustrates one method by which members of this new group of compounds may be prepared, but is in no way to be construed as limiting the invention thereto:

The preparation of h'iclilorotetrafluordtflfluoromethyDcyclohexadiene and tetrachlorotrifluoro(trifluoromethyl)cyclohexadiene was accomplished as follows: A suspension of silver difluoride (1000 grams) in a liquid fluorocarbon medium was cooled to zero degrees centigrade and 150 grams of pentachlorobenzotrifluoride was added thereto with constant stirring over a period of four hours. Stirring was continued for an additional three hours, after which the reactionmixturewasextractedthreetimeswitha 2 fluorocarbon. The organic products were then distilled and the following fractions separated: (1) 100 grams, boiling from to 80 centigrade at ten mm. of Hg; (2) 24 grams, boiling from 80 to 115 centigrade at ten mm. of Hg. The third fraction consisted of starting material. Fraction (1) was rectifled and yielded two products, trichlorotetrafluoro(trifluoromethyl)cyclohexadiene and tetrachlorotrifluoro(trifluoromethyl) cyclohexadiene, identified as follows:

Per cent Chlorine Compound 3. P., O.

\ Found Theory monitor. so at 11 mm. Hg..." as 2 33.0 mold-tor... 75 at 10 mm. Hg 40. 9 41. 7

We claim: 1. A perhalo(trifluoromethyl)cyclohexadiene,

selected from the group consisting of (1) trichlorotetrafluoro (trifluoromethyl) cyclohexadiene, CeClsFa-Cih, having a boiling point of approximately degrees centigrade at 11 millimeters of mercury pressure, and (2) tetrachlorotrlfluoro(trifluoromethyl) cyclohexadiene,

Cam's-CF:

having a boiling point of approximately degrees centigrade at 16 millimeters of mercury pressure.

2. Trichlorotetrailuoro (trifluoromethyl) cyclohexadiene, having a boiling point of approximately 50 degrees centigrade at 11 millimeters of mercury pressure.

3. Tetrachlorotrifluoro (trifluoromethyl) cyclohexadiene, having a boiling point of approximately 75 degrees centigrade at 18 millimeters of mercury P1388111.

WALDO B. HGEI'I'. EARL '1. MGBEE. VINCENT V. IJNDGREN.

REFERENCES CITED The following references are of record in the flle of this patent:

van der Linden: Rec. trav. chim. des Pays- Bas, 57, 1075-86 (1938).

Van der Linden: Rec. trav. chim. des Pays- 

1. A PERHALO(TRIFLUOROMETHYL)CYCLOHEXANDIENE, SELECTED FROM THE GROUP CONSISTING OF (1) TRICHLOROTETRAFLUORO (TRIFLUOROMETHYL) CYCLOHEXADIENE, C6CL3F4$CF3, HAVING A BOILING POINT OF APPROXIMATELY 50 DEGREES CENTIGRADE AT 11 MILLIMETERS OF MERCURY PRESSURE, AND (2) TETRACHLOROTRIFLUORO(TRIFLUOROMETHYL)CYCLOHEXADIENE, 